During a speech on Monday, Sen. John McCain did not mince words about Trump's defense of Tiki-Torch Nazis, and in particular warned against "half-baked, spurious nationalism."

President Trump joined the conservative talk show "The Chris Plante Show," and responded by threatening the Senator from Arizona, who's fighting brain cancer.

Host Chris Plante, a regular guest on Fox News, interviewed Trump today. The so-called president spent the interview bragging about himself and complaining that Sen. McCain voted down his healthcare plan.

Trump said, "We need some votes from some of the Republicans, for some reason they weren't there on healthcare. We thought we had it, but John McCain voted no, which was a shocker.

Plante jumped in, "He was taking shots at you again yesterday." He continued, "You heard what he said yesterday, Sen. McCain?"

Trump said, "Yeah, well I hear it and people have to be careful because at some point I fight back."

"I'm being very nice. I'm being very, very nice. But at some point I fight back, and it won't be pretty," he said.

Trump threatens to go after the man that is fighting for his life dealing with cancer?

What a tough guy.